Official spoiler alert today coming from Games Workhop on exactly who Alpharius is, and why no one can really track down where he is, or if he is even still alive.
via the Warhammer Community
https://www.warhammer-community.com/2018/06/04/who-is-alpharius-contains-mild-spoilers/
SPOILER BELOW
Get ready to have your mind blown, because Alpharius is not one Primarch, but two!
Ok, so most folk familiar with the Alpha Legion by this point probably knew that already, but it’s a pretty big deal – Alpharius, and his identical brother, Omegon, are the only twins in the Primarch brotherhood – a truth they keep jealousy hidden from most within their Legion, and all outside of it.
Both brothers pose, when necessary, as “Alpharius the Primarch”, as well as passing as a mere legionary in the ranks when the situation demands it. Moreover, other non-Primarch legionaries often pose as Alpharius in both war and diplomacy, so that the real identity and whereabouts of their Primarch is always in doubt.
IN GAMES
The rules to use Alpharius in the Age of Darkness games are very characterful.
His statline is as you would expect of a Primarch – lots of 6s and 7s, with a bucketload of wargear and special rules.
Where he really comes into his own, though, is with the One of Many rule, which basically allows Alpharius to pose as a standard legionary in your army until such a time as you wish to reveal him. This is not only very thematic but pretty handy for getting your valuable Primarch across the battlefield without the enemy being confident of what to be shooting at to stop him. This becomes even more effective when you factor in Mutable Tactics, a Legion ability that can give to your ENTIRE Alpha Legion army access to the Infiltrate or Scout special rules!
When he is ready to reveal his true identity, the fun really starts – clad in his trademark armour, the Pythian Scales, Alpharius is every inch a Primarch (except when he isn’t). As such, he’s naturally a combat monster, and with a tasty AP1, Armourbane, and an Instant Death close combat weapon, there’s very little he can’t handle – though he particularly excels at slicing up elite infantry, Mechanicum automata and characters. And the icing on the multi-headed cake is that, while he’s on the table, your whole army benefits from Preferred Enemy.
